Relation hierarchies

The map also supports nested relations, i.e. relations that contain relations themselves. These hierarchies are used in two different ways in the OSM database: they are either used to split up very long routes (e.g. E1) or they are used to avoid duplicated work where two routes go along the same way (see for example, the Swiss Via Francigena which is part of the European Via Romea Francigena). In the first case the sub-relations are not complete routes themselves and should therefore not be shown on the map independently.

How exactly a subrelation is treated by the renderer depends on the network tag:

  • If parent and child relation share the same network tag, the child relation is taken to be just a stage of the parent relation. Thus, its route is added to the parent relation and the child relation is not shown in the map.
  • If the network tag of parent and child relation are different, the relation are assumed to be independent. The route of the child relation is added to the parent and both relations are shown in the map.

Note: you can always inspect subrelations via the route browser. Simply select the parent relation and a selectable list of its subrelations is shown.